If the lamp lights up, but flickers, locate the trouble before attempting to do an endoscopy. If shaking the carrier cord-terminal produces flickering there may be a film of corrosion on the central contact of the light carrier that goes into the carrier cord-terminal.
If the lamp fails to show a light, the trouble may be in one of five places which should be tested for in the following order and manner. 1. The lamp may not be firmly screwed into the light-carrier. Withdraw the light-carrier and try screwing it in, though not too strongly, lest the central wire terminal in the lamp be bent over. 2. The light-carrier may be defective. 3. The cord may be defective or its terminals not tight in the binding posts. If screwing down the thumb nuts does not produce a light, test the light-carrier with lamp on the other cords. Reserve cords in each pair of binding posts are for use instead of the defective cords. The two sets of cords from one pair of binding posts should not be used simultaneously. 4. The lamp may be defective. Try another lamp. 5. The battery may be defective. Take a cord and light-carrier with lamp that lights up, detaching the cord-terminals at the binding posts, and attach the terminals to the binding posts of the battery to be tested.
Efficient use of forceps requires previous practice in handling of the forceps until it has become as natural and free from thought as the use of knife and fork. Indeed the coordinate use of the bronchoscopic tube-mouth and the forceps very much resembles the use of knife and fork. Yet only too often a practitioner will telegraph for a bronchoscope and forceps, and without any practice start in to remove an entangled or impacted foreign body from the tiny bronchi of a child. Failure and mortality are almost inevitable. A few hundred hours spent in working out, on a bit of rubber tubing, the various mechanical problems given in the section on that subject will save lives and render easily successful many removals that would otherwise be impossible.
It is often difficult for the beginner to judge the distance the forceps have been inserted into the tube. This difficulty is readily solved if upon inserting the forceps slowly into the tube, he observes that as the blades pass the light they become brightly illuminated. By this light reflex it is known, therefore, that the forceps blades are at the tube-mouth, and distance from this point can be readily gauged. Excellent practice may be had by picking up through the bronchoscope or esophagoscope black threads from a white background, then white threads from a black background, and finally white threads on a white background and black threads on a black background. This should be done first with the 9 mm. bronchoscope. It is to be remembered that the majority of foreign body accidents occur in children, with whom small tubes must be used; therefore, practice work, after say the first 100 hours, should be done with the 5 mm. bronchoscope and corresponding forceps rather than adult size tubes, so that the operator will be accustomed to work through a small calibre tube when the actual case presents itself.
[120] Cadaver Practice.—The fundamental principles of peroral endoscopy are best taught on the cadaver. It is necessary that a specially prepared subject be had, in order to obtain the required degree of flexibility. Injecting fluid of the following formula worked out by Prof. J. Parsons Schaeffer for the Bronchoscopic Clinic courses, has proved very satisfactory: Sodium carbonate—1 1/2 lbs. White arsenic—2 1/2 lbs. Potassium nitrate—3 lbs. Water—5 gal.
Boil until arsenic is dissolved. When cold add:
Carbolic acid 1500 c.c.
Glycerin 1250 c.c.
Alcohol (95%) 1250 c.c.
For each body use about 3 gal. of fluid.
The method of introduction of the endoscopic tube, and its various positions can be demonstrated and repeatedly practiced on the cadaver until a perfected technic is developed in both the operator and assistant who holds the head, and the one who passes the instruments to the operator. In no other manner can the landmarks and endoscopic anatomy be studied so thoroughly and practically, and in no other way can the pupil be taught to avoid killing his patient. The danger-points in esophagoscopy are not demonstrable on the living without actually incurring mortality. Laryngeal growths may be simulated, foreign body problems created and their mechanical difficulties solved and practice work with the forceps and tube perfected.
Practice on the Rubber-tube Manikin.—This must be carried out in two ways. 1. General practice with all sorts of objects for the education of the eye and the fingers. 2. Before undertaking a foreign body case, practice should be had with a duplicate of the foreign body.
It is not possible to have a cadaver for daily practice, but fortunately the eye and fingers may be trained quite as effectually by simulating foreign body conditions in a small red rubber tube and solving these mechanical problems with the bronchoscope and forceps. The tubing may be placed on the desk and held by a small vise (Fig. 72) so that at odd moments during the day or evening the fascinating work may be picked up and put aside without loss of time. Complicated rubber manikins are of no value in the practice of introduction, and foreign body problems can be equally well studied in a piece of rubber tubing about 10 inches long. No endoscopist has enough practice on the living subject, because the cases are too infrequent and furthermore the tube is inserted for too short a space of time. Practice on the rubber tube trains the eye to recognize objects and to gauge distance; it develops the tactile sense so that a knowledge of the character of the object grasped or the nature of the tissues palpated may be acquired. Before attempting the removal of a particular foreign body from a living patient, the anticipated problem should be simulated with a duplicate of the foreign body in a rubber tube. In this way the endoscopist may precede each case with a practical experience equivalent to any number of cases of precisely the same kind of foreign body. If the object cannot be removed from the rubber tube without violence, it is obvious that no attempt should be made on the patient until further practice has shown a definite method of harmless removal. During practice work the value of the beveled lip of the bronchoscope and esophagoscope in solving mechanical problems will be evidenced. With it alone, a foreign body may be turned into favorable positions for extraction, and folds can always be held out of the way. Sufficient combined practice with the bronchoscope and the forceps enable the endoscopist easily to do things that at first seem impossible. It is to be remembered that lateral motion of the long slender tube-forceps cannot be controlled accurately by the handle, this is obtained by a change in position of the endoscopic tube, the object being so centered that it is grasped without side motion of the forceps. When necessary, the distal end of the forceps may be pushed laterally by the manipulation of the bronchoscope.